It is known to record data marginally on a photographic film strip in correspondence with the film frames to which the data relates, and to coordinate the reading/writing of said data with the operation of an electric motor drive film transport mechanism. The data may, for example, be marginally encoded by optical means adjacent a frame at the time of exposure and relate to exposure parameters for later reference in producing prints from the developed negatives. An electric drive may be configured to delay the frame-to-frame advance of the film following exposure, until the data recording cycle is complete. See, e.g., Kazumi U.S. Pat. No. 4,588,274 and Harvey U.S. Pat. No. 4,973,996.
The provision of a magnetic recording track on a still camera roll film for the purpose of storing various frame specific fiducials relating to image exposure (such as the photographic day, exposure conditions, photographic place, photographer, data for photographic laboratory use, and the like) is disclosed in Ohta U.S. Pat. No. 4,613,911. Ohta suggests the use of such track as a recording medium for providing the camera with information regarding film sensitivity, or the number of exposed or unexposed frames. Williams U.S. Pat. No. 2,674,009 shows the use of marginal magnetic cue marks in the form of microscopically thin metal disks which can be detected by magnetic scanning heads for the purpose of instituting an event or series of events (control or variation of printing light intensity, etc.) when a predetermined point or points are reached during the course of travel of a motion picture film.
Harvey U. S. Pat. No. 4,987,431, issued Jan. 22, 1991, disclosed the use of magnetically prerecorded frame correlated data for accomplishing the frame-to-frame film transport metering and registration procedure between exposures. A magnetic read head acts to read frame-specific identifying cues spaced in frame length intervals magnetically prerecorded along a magnetic medium which extends lengthwise along one edge of the film. Film recording and registration is established by controlling an electric drive motor in accordance with data read from the medium by a read head during the film transport process. A microcomputer act to compare the identification number of a frame nearest the aperture station with the previously stored identification number of the desired next exposure frame to assure their identity. If they are not the same, the microcomputer activates the electric motor of the film transport drive to adjust the frame position to ensure correct registration of the desired next available exposure.
In gathering film resident, magnetically recorded data from a film strip during film transportation (such as the gathering of film speed, mid roll interrupt, etc. information during a film prewinding load cycle), a problem may exist where electromagnetic interference occurs during execution of the magnetic read command. The potential for electromagnetic interference is especially great if the electric drive motor is placed physically close to the magnetic read head in the camera. One approach to alleviate this problem is to use magnetic shielding to separate the read/write elements from the potential source of interference. It is desirable to find an alternative approach to addressing this problem that eliminates totally the source of interference during the read process.